Guided bone rasp

ABSTRACT

A surgical tool for use in preparing a graft path in anterior cruciate ligament reconstruction in a knee joint in which aligned tibial and femoral osseous tunnels are made for a bone-tendon-bone graft or similar surgery where two bone tunnels are in alignment. The tool comprises an elongated guide body having a guide shaft capable of being positioned within the tibial tunnel and extending into the femoral tunnel, and an elongated channel-like main body which is coaxial with the guide shaft. The main body includes a rasping head and is rotatably and axially slidable on the guide shaft for guided rasping of bone surfaces along the graft path. The rasp head fully encircles the guide shaft and is capable of following the guide shaft to enter and extend beyond the tibial tunnel. The leading end of the guide body includes a guide head with a flexible structure for connecting the head to the guide shaft. The guide head is movable through the tibial tunnel and into the femoral tunnel to position the guide shaft for subsequent rasping of surfaces along the graft path by manually moving the rasping head along and/or about the shaft. The flexible connection of the guide head to the guide shaft enables the knee to be flexed with the guide body is in place for inspection of the graft path in the area of the intercondylar notch while the rasping body may serve as a trial prosthesis to check for interference.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of application Ser. No. 08/373,663filed Jan. 17, 1995, now U.S. Pat. No. 5,601,561.

FIELD OF INVENTION

The present invention is in the field of orthopedic surgical tools.

BACKGROUND OF THE INVENTION

Surgical techniques for the reconstruction of the anterior cruciateligament (ACL) within the knee joint have typically involved creatingosseous tunnels open at each end in the tibia and femur. One end of asynthetic or natural graft is placed into and anchored in eachrespective tunnel with the graft in tension. The graft extending betweenthe femur and tibia thus serves as a replacement for the ACL. Such aprocedure has commonly involved surgical incisions both above and belowthe knee to provide access to the femoral and tibial tunnel openings. Insuch surgery a tool which has been commonly used is a device sold by W.L Gore & Associates and known by the trademark "GORE SMOOTHER CRUCIALTOOL." This tool is a multi-function disposable instrument that serves:

1) as a trial prosthesis for assessment of the intercondylar notch,

2) to smooth the intercondylar notch and drill hole edges afterdrilling,

3) as a measurement gauge for proper selection of graft length, and

4) to engage and place a biologic or synthetic graft.

This prior art tool as shown in FIGS. 7 and 8 is comprised of a flexiblemain body 51 of silicone elastomer extruded onto stainless steel cable.The exterior surface of the silicone is then printed with measuringmarks at 2 centimeter increments. A flexible braid 55 of stainless steelcable in an open pattern covers a major portion of the silicone. Arelatively stiff stainless steel segment having an "eye" at its end andencased in polytetrafluoroethylene (PTFE) extends from one end of themain body and forms the leading end 52 of the tool. A flexible aramidfiber loop 53 extends from the other end of the main body as a trailingend of the tool. In use, the surgeon drills entry holes into thepatient's tibia, below the joint, and femur, above the joint. Theleading end of the tool is introduced into the tibial tunnel, across theknee joint space and into the femoral tunnel to exit laterally on thefemur. At this point the trailing end of the tool will still protrudefrom the tibial tunnel. The main body of the tool is held in tension andslid back and forth through the bone tunnels so that the slightlyabrasive surface of the open braid covering the main body may smooth thebone surfaces and edges along the path for the graft. The measuringmarks assist in determining proper graft length. Once in place in thegraft path the device functions as a trial prosthesis by allowingarthroscopic inspection for visual determination of whether the graftposition will allow for free joint movement without impingement orinterference between any tissue or bone. The flexible loop on thetrailing end of the tool is attached to the ACL graft which is thenpulled into position within the bone tunnels as the tool is removedthrough the femoral opening.

More recently, alternative endoscopic surgical techniques for thereconstruction of the anterior cruciate ligament (ACL) within the kneejoint have been developed so that the placement of a graft between thefemur and tibia may be accomplished using a technique requiring only asingle external skin incision. The graft is commonly one continuouspiece of tissue taken from the patient's own knee and comprisingsections or plugs of patella bone and tibial bone connected by a sectionof patellar tendon. Accordingly such a graft may be referred to as a"Bone-Patellar Tendon Bone" graft or simply as a "BPTB" graft. In thismore recent technique an open tibial tunnel is created to extendupwardly to exit the head of the tibia. This tibial tunnel is orientedso that a blind femoral tunnel may be bored using the tibial tunnel foraccess when the knee is flexed at, for example, approximately 60 to 80degrees. Accordingly with the joint flexed, the femoral tunnel is inalignment with the tibial tunnel and creates an essentially straightpath for placement of the graft. The obvious advantage to the patient ofthis improved technique is that it is less invasive since it cancompletely eliminate the need for an incision in the thigh and theadditional trauma and morbidity which may be associated with thatincision. However because the path of the graft does not involve twoopen ended osseous tunnels, the described flexible prior art tool ofFIGS. 7-8 is not suitable for use with the improved technique.

The surgical procedure for ACL reconstruction for which the presentinvention is intended has been described by authors Douglas W. Jackson,MD; Robert Kenna; Timothy M. Simon, MS; and Peter Kurzweil, MD; in"Orthopedics" Volume 16, Number 9, (September 1993) under the title"Endoscopic ACL Reconstruction." The relevant portion of the describedprocedure is briefly summarized as follows:

Work within the joint itself is viewed arthroscopically and accomplishedthrough anterolateral and anteromedial portals. The respective tunnelsare bored in the tibia and femur, with the tibial tunnel exiting thetibial head in the area of the intercondylar eminence. A 2.4 mm eyeloopdrill is drilled into place to be used as a guide for a cannulatedreamer which creates the femoral osseous tunnel. The eyeloop drill maybe drilled completely through the femur and out the anterolateral aspectof the thigh and be used later to pass sutures attached to the graft topull and guide the graft into place. The blind femoral tunnel is boredbeyond, and in alignment with, the tibial tunnel to a depth ofapproximately 25 mm, or slightly more than the length of the patellarbone plug, by a tool extending through the tibial tunnel with the kneeflexed at approximately 70 degrees from the fully extended or "straightleg" orientation. The diameter of the femoral tunnel may initially besomewhat undersized in order to allow adjustment of the tunnel positionafter the initial drilling.

SUMMARY OF THE INVENTION

The present invention relates to a rasping tool to facilitate thepreparation of bone surfaces, particularly those between osseous tunnelsand in the area of the intercondylar notch, to create an acceptable pathfor placement of a graft using the single incision endoscopic technique.Typically, the femoral and tibial tunnels and a harvested bone-patellartendon-bone graft are initially prepared so that the tunnels andrespective bone plugs are precisely sized to match one another. However,while the tunnels themselves may be accurately drilled with the kneejoint in one position, it may be necessary to accurately remove bonematerial from areas between the respective tunnels to insure that thegraft path remains unobstructed during the range of motion of the kneejoint.

In particular, the present tool provides a manual means of accuratelyremoving and/or smoothing bone surfaces and edges to prepare a graftpath to insure the graft is free of any impingement with bone and/orother tissue during movement of the knee joint through its full range ofmotion.

The tool itself comprises an external elongated semi- cylindrical orchannel-shaped rigid main body of stainless steel which is coaxial withan internal elongated cylindrical rigid guide body shaft.

A guide head sized to fit accurately within a femoral tunnel is flexiblyconnected to the guide body shaft using a joint material of siliconecovered stainless cable. The guide head can accordingly remain in placeas the knee joint is flexed. Use of such a joint structure provides anumber of desirable characteristics. The central wire gives the jointmaterial the characteristic of being resilient and longitudinallynon-extensible. While the joint is fully flexible and movable, it has adegree of "memory" which causes the guide head to tend to return to aposition in which it aligned with respect to the guide shaft. Thisparticularly desirable to maintain alignment of the guide head with theguide shaft for initial insertion of the guide shaft and head throughthe tibial tunnel and into the femoral tunnel. Additionally, the coveredcable (1) is flexible in any direction from its axis, (2) provides aflexible joint in a relatively short space, (3) provides a smoothexterior surface which does not tend to accumulate any tissue or debris,and (4) provides a smooth exterior surface which is readily cleaned andsterilized. The covered cable is also essentially sealed against anyinfiltration of debris or tissue which might create a binding effect ormechanically interfere with its movement or flexibility as could readilyoccur with a mechanically hinged joint.

The rasp body is provided with an abrasive or cutting surface over aportion of it exterior circumference. The tool allows accurately guidedrotary and reciprocating manipulated operation of the rasp portionthroughout a range of knee joint motion to facilitate preparation of thegraft path within and between the osseous tunnels required when used inconjunction with single incision ACL reconstructive surgery where atleast one of the osseous tunnels is blind or only open at one end.

The present invention provides numerous functions and benefits overprior tools:

1. The device serves as a trial prosthesis for assessment of the graftpath in the area of the intercondylar notch.

2. The abrasive rasp surface on the guided head end of the main body maybe used to smooth bone edges and surfaces along the graft path, andparticularly within the intercondylar notch.

3. Markings may be placed on the guide body to serve as a measurementgauge for proper selection of graft length.

4. The movement of the rasp surface of the rasping head is guided formanual rotation and/or reciprocation by means positioned within a bonetunnel so that the rasping function can be more accurately controlledthan is the case with cutting or abrading tools which are operated in afree-hand or unguided manner or which have abrading surfaces which areinherently flexible.

5. The precise control of the rasping function helps to minimizeunnecessary removal of bone material.

6. In contrast to the described prior art tool, the exposure of the raspsurface portion of the cylindrical rasp head is circumferentially andaxially limited to allow selective rasping action thereby minimizing thepossibility of damage to bone or tissue which is not to be removed orsmoothed.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the assembled device of the preferredembodiment.

FIG. 2 is a plan view of the guide body of the preferred shown in placewithin the main body.

FIG. 3 is a plan view of the leading and trailing portions of the guideshaft of the preferred embodiment.

FIG. 4 is a plan view of the main body of the preferred embodiment.

FIG. 5 is a cross-section of the guide shaft and rasp head of the mainbody taken at A--A of FIG. 1.

FIG. 6a is a partial cross-section of the end of the guide shaft andflexible joint taken at B--B of FIG. 1 showing a ferrule used to attachthe flexible joint material into the shaft prior to longitudinalcrimping of the ferrule.

FIG. 6b is a partial cross-section similar to FIG. 6a showing a ferrulecrimped onto the joint cable and crimped into the guide shaft.

FIG. 7 is a plan view of a prior art device.

FIG. 8 is a perspective view of a prior art device in place within thebone tunnels.

FIG. 9 is a cross-sectional view of a flexed knee joint showing alignedbone tunnels with the guide body of the preferred embodiment in placeand the rasp head retracted.

FIG. 10 is a cross-sectional view of a straightened knee joint showingthe bone tunnels with the device of the preferred embodiment in placewith the rasp head extended into the joint space.

FIG. 11 is a cross-section of the guide head of the device of thepreferred embodiment taken at C--C of FIG. 1 showing the guide headprior to crimping.

FIG. 12 is view similar to FIG. 11. showing the radial crimping of theguide head.

FIG. 13 is a plan view of the end surface of the guide of the preferredembodiment showing apertures for affixing sutures.

FIG. 14 is a cross-section of the guide shaft and main body takenthrough the thumb brace and corresponding to D--D of FIG. 1, showing oneextreme position of the relative rotation between the main body andguide shaft.

FIG. 15 is a view similar to FIG. 14 showing an opposite extreme ofrelative rotation between the main body and guide shaft.

DETAILED DESCRIPTION OF THE INVENTION

The tool of the present invention comprises a main body 1 of stainlesssteel about 10.75 in. (273 mm) in length having a center or intermediateportion 2 of an elongated hollow semi-cylindrical cross sectionapproximately 5.5 in. (104 mm) in length and 0.275 in. (7 mm) in outsidediameter forming an open-sided guide channel 3 which mates with acoaxial guide shaft assembly 8. Rigidly fixed to one end of the centerportion 2 of the body is a hollow cylindrical rasp head portion 6 about0.75 in. (19 mm) in length with a diameter of approximately 0.4 in. (10mm). The rasp head 6 is provided with an abrasive or rasp-like exterior7 over about half of its circumference or an essentially semicylindricalportion of its surface. As illustrated in the figures, thesemicylindrical rasp surface will typically be oriented with respect tothe rasp body to encircle a portion of the circumference of the raspbody corresponding to that portion encircled and defined by thesemicylindrical guide channel 3. The rasp surface may be a machined,knurled or textured area to provide a toothed, file-like surface with anabrasive or cutting ability sufficient for removing bone. Alternativelythe rasp surface may be essentially abrasive and created usingrecognized methods of permanently attaching diamond dust or othersuitable abrasive to the rasp head surface.

At an opposite end of the central portion of the main body a handleportion 4 provides a comfortable means of manually grasping andmanipulating the rasping portion of the tool device. The handle ispreferably provided with a longitudinal full-length cylindrical bore 5of the same inner diameter as the guide channel 3 and which exits at thebase of the handle 4 and which creates an extension of the guide channel3. This central bore 5 is open at each end to facilitate cleaning andsterilization of the device.

The guide body assembly is comprised of a guide head 20 flexiblyattached to a leading end of a guide shaft 8 having aligned coaxialleading shaft portion 10 and trailing shaft portion 11 of tubularstainless steel which are coupled together end-to-end using a commonmale/female threaded connection 12 or other suitable detachable jointstructure in the assembled device. To facilitate assembly or disassemblyof the threaded guide shaft connection, one or both of the two shaftportions 10 and 11 is provided with a short area 13 upon its exteriorsurface having two opposite flattened parallel faces as means forengagement with a wrench or similar tool to allow application ofsufficient torque to securely tighten or loosen the threaded joint 12.

The trailing shaft portion 11 of the guide body assembly isapproximately 5.125 in. (130 mm) in length and is provided with arigidly secured manually engageable thumb or finger brace 14 extendinggenerally perpendicular to the shaft axis near the joint end of thisshaft portion and providing a broad flat planar surface against which athumb or finger may rest. The guide head 20 is a rigid, generallycylindrical structure of suitable material, such as stainless steel,approximately 1 in. (25 mm) in length and 0.3 in. (8 mm) in diameter orof a size and/or shape which will correspond closely to the length anddiameter of the prepared femoral tunnel. The transverse surface or endface 21 of the tip of the head is generally flat and circular to seatagainst the transverse end of a femoral tunnel. The sides of the headmay be partially cut away or longitudinally grooved except at its tip orcircular end face 21. As can be seen in FIG. 13 the tip is provided withone or more pairs of an aperture 22 and a notch 23 extending through thetip to one of the grooves 24 to allow tying or affixing suture materialto the guide head to provide a means of (1) pulling the head of theguide body assembly of the device into position in the femoral tunnel,or (2) securing the guide body assembly of the device once it is inposition. A suture or similar threadlike material for this purpose canbe drawn into the tibial and femoral tunnels using the thin elongatedeye-loop drill which also serves as an axial guide for a tubular orcannulated reamer used in drilling the femoral tunnel. The eyeloop drillis externally accessible when it is drilled completely through the femurand out the anterolateral aspect of the thigh and through the skin.

The guide head 20 is joined to the guide body by means of a short lengthof flexible and durable joint material 15 such as a sleeve of siliconeelastomer 16 or similar smooth-surfaced flexible plastic materialextruded onto a flexible stainless steel cable 17 and having a diameterof approximately 0.15 in. (4 mm).

While the joint material may be adhered into the guide head and theleading end of the leading shaft portion of the guide body using asuitable adhesive, such as a settable or curable silicone, it may bedesirable to use recognized inert materials and strictly mechanicalmethods of securing these respective elements together to minimizeproblems which may be inherent in the use of the tool as a surgicalinstrument. Of primary concern are minimizing any potential adversereaction to foreign materials introduced even temporarily into apatient's body, and insurance of the structural integrity of the deviceduring surgical use. The avoidance of chemical adhesives may helpminimize any possibility of a patient's adverse reaction to suchchemicals. Since the device is intended for reuse, a mechanical joint isalso likely to be more tolerant to repeated cleaning and heatsterilization of the device. Accordingly, in order to insure a securemechanical attachment of the joint material into the guide head thejoint material may be crimped in place. An appropriate method of suchcrimping is illustrated in the cross section shown in FIG. 12. Thelongitudinal flutes or grooves 24 in the outer cylindrical surface ofthe guide head 20 result in thinner walls 25 in the areas of the flutesand thereby allowing greater deformability of the walls of the head,which are forced inwardly about the core cable 17 of the joint material16 as the walls 25 are compressed radially inward.

Secure attachment of the flexible joint material into the leading end ofthe guide shaft may be accomplished, by first securing the jointmaterial into a stainless steel ferrule 29 using a novel longitudinalcrimping of the ferrule. A portion of the silicone covering sleeve 16 isremoved to expose a portion of the core cable 17 to be inserted into theferrule. To allow the crimped ferrule to maintain a rigid cylindricalouter surface which will fit snugly into the hollow end of the guideshaft, it is desirable to avoid distorting the circular cross section ofthe ferrule as might occur if the ferrule 29 were to be compressedmerely radially to, for example, form an annular impression to crimp itin place onto the joint material. The crimping function of the ferrulein the present invention is therefore accomplished by providing theferrule with one or more crimp structures comprising an annular groove26 separating two barrel-like sections 27 and 28 of the ferrule body. Asshown in FIG. 6b, as these two body sections 27 and 28 are pressedaxially toward one another and into engagement, the groove 26 is closedand the ferrule material 30 between the respective body sections isdistorted and displaced radially inwardly to tighten about the core wireof the joint material and anchor the ferrule. Thus, the ferrule 29 iscrimped in place without any significant diametric change or distortionof its external cylindrical shape. The ferrule with the cable crimpedtherein is then placed into the tubular leading end portion 40 of theguide shaft 10 and secured using one or more annular grooves 41 pressedor knurled into the exterior of the wall of the guide shaft end portionto deform an annular portion of the wall inwardly to positively engage acorresponding annular groove 42 in the exterior of the ferrule. Theferrule groove may be preformed or formed during the crimping of thetubular shaft onto the ferrule.

While the described structures for attaching the ends of the jointmaterial to the respective portions of the guide body assembly aremechanically sound, there are medical concerns stemming from thereusability of the device which may also be taken into account.Accordingly, it may be desirable to provide a slight cylindrical recesswithin the joint end of guide head 20 and ferrule 29 where such recessis sized to accommodate and seal snugly around the circumference of anend of the silicone covering 16 of the joint material so as to minimizeor eliminate surface gaps, or similar areas which might trap oraccumulate tissue or debris as the joint material flexes.

The tool is assembled by placing the trailing portion 11 of the guideshaft into the guide channel 3 of the main body with the internallythreaded joint connection end toward the rasp head. The externallythreaded joint connection end of the guide shaft is insertedlongitudinally into the guide channel though the hollow rasp head tomeet with the joint end of the trailing portion of the guide shaft andthe guide shaft portions are threaded together to form the completeguide shaft.

Once the device is assembled as described with the respective guideshaft portions threaded together, the guide shaft assembly cannot beremoved from the main body without first disengaging the guide shaftsections. The tool is disassembled into three primary parts for cleaningand sterilization by merely reversing the assembly sequence.

The tool is used following the drilling of the respective tibial andfemoral osseous tunnels. As shown in FIG. 9, with the knee jointinitially flexed so as to align the respective bone tunnels and with theguide head oriented to be essentially coaxial with the guide shaft, theguide shaft of the assembled tool is fully axially extended beyond therasping head and may be inserted head first into the tunnel within thetibia T, across the joint space and into the tunnel within the femur F,using the finger brace 14. Alternatively the guide head may be secured,using sutures attached through holes 22, to the trailing end of a guidewire or drill guide and pulled into place. The guide head thus becomesseated within the femoral tunnel while the flexible joint of the guidebody is positioned generally within the joint space and the guide shaftis positioned generally within the tibial tunnel and extending at leastpartially into the joint space. At this point the rasping head 6 aroundthe guide shaft is still outside the tibial tunnel as seen in FIG. 9.The flexibility of joint between guide head and guide shaft allows theseparts of the device to remain in position during virtually any flexionof the knee joint. As the knee is moved through a range of motion, thejoint can be visually inspected for any material which might causeinterference or impingement within or along the graft path. The mainbody 1 can be longitudinally slid or rotated upon the guiding shaft 8 toselectively and accurately abrade or cut bone material and therebyappropriately shape and smooth the bone surfaces and edges along thegraft path. As shown in FIGS. 14 and 15, the main body can be rotatedabout the guide shaft through an angle of nearly 180 degrees with therotational movement being blocked at each end of the such rotation by anedge 43 of the semicylindrical guide channel 3 coming into contact withthe base of the thumb brace 14.

While all or a portion of the cylindrical surface of the rasp head maybe provided with a rasp surface, it will generally be desirable to limitthe rasp surface to, for example, a semicylindrical surface so that therasping action may be confined to chosen areas in order to preventdamage to bone or tissue, such as existing ligaments, which mightotherwise be likely to inadvertently come into contact with a portion ofthe rasp surface. However even with the rasp surface covering onlyapproximately 180 degrees of the cylindrical surface of the rasp head,the guide shaft assembly carrying the main body may be rotated so thatat least a portion of the rasp surface may be selectively engaged with aportion of nearly the entire circumferential area surrounding the tool.This circumferential area would correspond, for example, to the fullouter surface of a bone-tendon-bone graft.

Other variations within the scope of this invention will be apparentfrom the described embodiment and it is intended that the presentdescriptions be illustrative of the inventive features encompassed bythe appended claims.

What is claimed is:
 1. An elongated guide body for use with an elongatedrasping body, said elongated guide body comprising a trailing shaftportion having a manually engagable brace generally perpendicularlyattached to the trailing shaft portion, said trailing shaft portionfurther having an end which is removably attachable to a first end of aleading shaft portion, and still further having a guide head flexiblyattached to a second end of the leading shaft portion, and wherein theelongated guide body forms in combination with the elongated raspingbody a surgical tool for the preparation of a graft path which includesa first and second tunnel in bone, the elongated guide body beingproportioned to allow the elongated rasping body to fit coaxially aboutthe leading shaft portion and to allow axial motion of the elongatedrasping body with respect to the elongated guide body.